1. Field of the Invention
The present invention relates to a contact probe pin used for testing electrical properties of a semiconductor device. More specifically, the present invention relates to a contact probe pin having durability high enough not to deteriorate in the electrical conductivity even by the repetition of the test.
2. Description of the Related Art
An electronic component such as integrated circuit (IC), large-scale integrated circuit (LSI) and light emitting diode (LED) (that is, an electronic component using a semiconductor device) is tested for its electrical properties by contacting a probe pin with the electrode of the semiconductor device. The probe pin (contact probe pin) used in such a testing apparatus (semiconductor testing apparatus) is required to, as well as having good electrical conductivity (low contact resistance value), have excellent durability to such an extent of not causing wear or damage even by the repeated contact with an electrode as a device under test.
The contact resistance value of the contact probe pin is generally set to 100 mΩ or less but is sometimes disadvantageously increased to from hundreds of mΩ to several Ω by the repeated testing with a device under test.
As for the measure to solve such a problem, cleaning of the contact probe pin or replacement of the contact probe pin itself is employed. However, such a measure incurs a significant reduction in reliability and operation rate of the test process, and it is demanded to realize a contact probe pin capable of bringing out properties of causing no disadvantageous increase in the contact resistance value even by the use over a long period of time. In particular, the device under test (electrode) formed of a material such as solder or tin plating has a property that the surface is susceptible to oxidization and at the same time, because of a soft material, the device under test is shaved off by the contact with the contact probe pin and is liable to adhere to the tip part of the contact probe pin making it difficult to perform stable contact.
As for the method to stabilize the contact resistance value, a technique of coating a carbon film on the vicinity of the tip part of the contact probe pin (the tip part coming into contact with the electrode and the vicinity thereof) has been proposed (see, for example, JP-A-2001-289874 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), JP-A-2002-318247, JP-A-2003-231203 and JP-A-2007-24613). An important requirement in this technique is to mix an alloy element such as tungsten (W) with the carbon film typified by diamond-like carbon (DLC) and form a surface film having both low adhesion to the device under test (electrode), which is attributed to the carbon film, and high electrical conductivity due to the action of the metal (or a carbide thereof) mixed.